From 4fd8b825f77c07453ad91261540efd044fa63f62 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lloren=C3=A7=20Muntaner?= <llorenc.muntaner@dfinity.org>
Date: Fri, 26 Jan 2024 16:55:00 +0100
Subject: [PATCH] Feat: Add `toE8s` to TokenAmountV2 (#529)

# Motivation

Support formatting e8s for tokens that have different decimals than 8.

# Changes

* Add method `toE8s` to `TokenAmountV2`.

# Tests

* Add tests for new method.

# Todos

- [x] Add entry to changelog (if necessary).

---------

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
---
 CHANGELOG.md                            |  1 +
 packages/utils/README.md                |  9 ++++
 packages/utils/src/parser/token.spec.ts | 72 +++++++++++++++++++++++++
 packages/utils/src/parser/token.ts      | 14 +++++
 4 files changed, 96 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 260f08f8..2e915419 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 - Add "API Boundary Node Management" topic support.
 - Add optional field `logo` to `Token` type.
 - Update `sns-js` candid files with new fields in sns canisters.
+- Add public method `toE8s` to `TokenAmountV2`.
 
 ## Breaking changes
 
diff --git a/packages/utils/README.md b/packages/utils/README.md
index aadabe87..861ee210 100644
--- a/packages/utils/README.md
+++ b/packages/utils/README.md
@@ -465,6 +465,7 @@ Represents an amount of tokens.
 - [fromString](#gear-fromstring)
 - [fromNumber](#gear-fromnumber)
 - [toUlps](#gear-toulps)
+- [toE8s](#gear-toe8s)
 
 ##### :gear: fromUlps
 
@@ -525,6 +526,14 @@ Parameters:
 
 [:link: Source](https://github.com/dfinity/ic-js/tree/main/packages/utils/src/parser/token.ts#L322)
 
+##### :gear: toE8s
+
+| Method  | Type           |
+| ------- | -------------- |
+| `toE8s` | `() => bigint` |
+
+[:link: Source](https://github.com/dfinity/ic-js/tree/main/packages/utils/src/parser/token.ts#L330)
+
 ### :factory: Canister
 
 [:link: Source](https://github.com/dfinity/ic-js/tree/main/packages/utils/src/services/canister.ts#L4)
diff --git a/packages/utils/src/parser/token.spec.ts b/packages/utils/src/parser/token.spec.ts
index 19f73ce6..a5eda444 100644
--- a/packages/utils/src/parser/token.spec.ts
+++ b/packages/utils/src/parser/token.spec.ts
@@ -347,6 +347,32 @@ describe("TokenAmountV2 with 18 decimals", () => {
       FromStringToTokenError.InvalidFormat,
     );
   });
+
+  it("returns the value in e8s", () => {
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "2", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(200_000_000n);
+
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "0.21", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(21_000_000n);
+
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "0.00021", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(21_000n);
+
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "2000", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(200_000_000_000n);
+  });
 });
 
 describe("TokenAmountV2 with 2 decimals", () => {
@@ -393,6 +419,26 @@ describe("TokenAmountV2 with 2 decimals", () => {
       }),
     );
   });
+
+  it("returns the value in e8s", () => {
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "2", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(200_000_000n);
+
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "0.21", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(21_000_000n);
+
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "2000", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(200_000_000_000n);
+  });
 });
 
 describe("TokenAmountV2 with 0 decimals", () => {
@@ -472,4 +518,30 @@ describe("TokenAmountV2 with 8 decimals", () => {
       TokenAmountV2.fromUlps({ token: token, amount: 0n }),
     );
   });
+
+  it("returns the value in e8s", () => {
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "2", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(200_000_000n);
+
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "0.21", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(21_000_000n);
+
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "0.00021", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(21_000n);
+
+    expect(
+      (
+        TokenAmountV2.fromString({ amount: "2000", token }) as TokenAmountV2
+      ).toE8s(),
+    ).toEqual(200_000_000_000n);
+  });
 });
diff --git a/packages/utils/src/parser/token.ts b/packages/utils/src/parser/token.ts
index d09b7153..266cc4df 100644
--- a/packages/utils/src/parser/token.ts
+++ b/packages/utils/src/parser/token.ts
@@ -322,4 +322,18 @@ export class TokenAmountV2 {
   public toUlps(): bigint {
     return this.ulps;
   }
+
+  /**
+   *
+   * @returns The amount of ulps in e8s precision
+   */
+  public toE8s(): bigint {
+    if (this.token.decimals < 8) {
+      return this.ulps * 10n ** BigInt(8 - this.token.decimals);
+    } else if (this.token.decimals === 8) {
+      return this.ulps;
+    } else {
+      return this.ulps / 10n ** BigInt(this.token.decimals - 8);
+    }
+  }
 }